The present invention relates to a thermally developable light-sensitive material, and more particularly to one that experiences only a small amount of fog during thermal development (this fog is hereinafter referred to as thermal fog).
The silver-image forming, thermally developable light-sensitive material to be processed for development by dry heat, has the disadvantage that an adequately high image density cannot be attained without increasing the level of fog, which is the minimum density obtained in the unexposed portions of the material.
Various compounds have been proposed for use in thermally developable light-sensitive materials as agents that are capable of preventing thermal fog (hereinafter also referred to as development restrainers). Examples of these agents include mercury compounds (U.S. Pat. No. 3,589,903), N-halogeno compounds (West German Pat. No. 2,402,161), Peroxides (West German Pat. No. 2,500,508), sulfur compounds (West German Pat. No. 2,617,907), palladium compounds (U.S. Pat. No. 4,102,312), sulfinic acids (Japanese Patent Publication No. 28417/1978), mercaptotriazoles (Research Disclosure Nos. 169077 and 169079), and 1,2,4-triazole (U.S. Pat. No. 4,137,079).
However, none of these development restrainers are completely satisfactory since they are either quite harmful to humans or low in their effectiveness in preventing thermal fog.
The present inventors previously filed Japanese Patent Application No. 66386/1984 wherein they proposed that a thermally developable light-sensitive material that will experience only a small degree of thermal fog can be attained by incorporating in at least one light-sensitive layer an antifoggant that consists of a hydroquinone or phenol derivative based compound and benzotriazole or a derivative thereof. However, the improvement achieved by this proposal was still unsatisfactory and it has been desired to offer a thermally developable light-sensitive material that will experience an even smaller degree of thermal fog.